JPS6239725B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a hard contact lens with excellent oxygen permeability and excellent machinability. Conventional contact lenses are broadly classified into hard and soft types. Rigid contact lens polymers, such as polymethyl methacrylate, have excellent machinability and dimensional stability, allowing contact lens lenses with stable power to be obtained, but their oxygen permeability is extremely poor.
On the other hand, polymers for soft contact lenses, e.g.
Hydrous polyhydroxyethyl methacrylate has better oxygen permeability than polymethyl methacrylate, but has lower mechanical strength and poor dimensional stability.
It is difficult to obtain contact lenses with stable power, and disinfection is necessary because they tend to serve as a suitable medium for the growth of bacteria. There are other silicone rubbers available as polymers for soft contact lenses, but although they have good oxygen permeability, they are elastic and have poor machinability, making them unsuitable for manufacturing corrective contact lenses, and they are also hydrophobic. Therefore, it has poor wetting properties with tear fluid and is less practical as a material for contact lenses. In view of the fact that there is currently little known about contact lens polymers that simultaneously satisfy oxygen permeability, machinability, dimensional stability, etc., as a result of intensive research, the present inventors discovered that styrene-based polymers The present invention was achieved by discovering that a copolymer of a monomer and bisphenol-A-dimethacrylate has excellent oxygen permeability and good machinability. That is, an object of the present invention is to provide a hard contact lens with good oxygen permeability and machinability. The contact lens according to the present invention is obtained by cutting and polishing a molded product made of a copolymer of one or more monomers represented by the following general formula () and bisphenol-A-dimethacrylate. (In the formula, R ₁ is H or CH ₃ , R ₂ is H,
CH ₃ , C ₂ H ₅ , C ₃ H ₇ , C ₄ H ₉ , OCH ₃ , Cl, NO ₂ ,
OH or _NH2 ). The preferred amount of the monomer of general formula () is 60 to 95
The preferred amount of bisphenol-A-dimethacrylate is from 5 to 40% by weight. If the amount of bisphenol-A-dimethacrylate used is less than 5%, the resulting molded product will be soft and difficult to cut and polish. On the other hand, the amount of bisphenol-A-dimethacrylate used was 40%.
If it exceeds this value, the molded product becomes brittle and its machinability also deteriorates. When styrene is copolymerized with commonly used crosslinking agents such as divinylbenzene, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, and trimethylolpropane trimethacrylate, both oxygen permeability and cutting abrasiveness deteriorate significantly. Only when the crosslinking agent bisphenol-A-dimethacrylate used in the present invention is copolymerized with a styrenic monomer, the oxygen permeability and cutting abrasiveness are improved over polystyrene. The oxygen-permeable contact lens of the present invention can be obtained by adding a polymerization initiator to the monomer mixture, polymerizing it by heating or irradiating with ultraviolet rays, and cutting and polishing the obtained molded product. In addition to the above monomers, a small amount of 2-hydroxy methacrylate, methacrylic acid, acrylic acid, vinylpyrrolidone, etc. can be copolymerized to further improve wettability. Next, the present invention will be explained in more detail with reference to Examples. The measurements and evaluations in Examples and Comparative Examples were performed as follows. (1) Oxygen permeability coefficient A disk sample with a diameter of 15 mm and a thickness of 0.20 mm was measured in water at 30°C using a Kaken film oxygen permeability meter (manufactured by Rika Seiki Kogyo Co., Ltd.). (2) Machining and polishing properties Spherical processing is performed using a small precision lathe, and
The spherical surface was polished with alumina, and those with a glossy surface were considered acceptable. Example 1 A mixture consisting of 95 parts of polymerized styrene, 5 parts by weight of bisphenol-A-dimethacrylate, and 0.2 parts by weight of benzoyl peroxide was placed in a test tube, and after the gas was replaced with nitrogen, the tube was sealed and placed in a hot air drying oven at 60°C. The sample was left at 90°C for 24 hours and further left at 90°C for 2 hours. After slowly cooling to room temperature, the polymer was taken out and its oxygen permeability coefficient and cutting workability were measured and evaluated. As a result, the oxygen permeability coefficient is 3.1×
10 ^-10 cc (STP)・cm/cm ²・sec・cmHg, cutting abrasiveness passed. Next, contact lenses of various compositions were produced using the same method as in Example 1, and the results of measurement and evaluation are shown in Table 1. As is clear from the results in Table 1, the contact lenses of the present invention had significantly improved oxygen permeability compared to conventional polymethyl methacrylate hard contact lenses, and had comparable machinability. Furthermore, although polystyrene has relatively good oxygen permeability, it has poor cutting and abrasive properties, making it impossible to produce contact lenses.

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Claims (1)

[Claims] 1 General formula () (In the formula, R ₁ is H or CH ₃ , R ₂ is H,
CH ₃ , C ₂ H ₅ , C ₃ H ₇ , C ₄ H ₉ , OCH ₃ , Cl, NO ₂ ,
OH or _NH2 ). 1. A hard contatlene lens with good oxygen permeability, characterized in that it is made of a copolymer of one or more monomers represented by the following and bisphenol-A-dimethacrylate.